Regulatory gamesmanship typically relies on a planning technique known as regulatory arbitrage, which occurs when parties take advantage of a gap between the economics of a deal and its regulatory treatment, restructuring the deal to reduce or avoid regulatory costs without unduly altering the underlying economics of the deal. This Article provides the first comprehensive theory of regulatory arbitrage, identifying the conditions under which arbitrage takes place and the various legal, business, professional, ethical, and political constraints on arbitrage. This theoretical framework reveals how regulatory arbitrage distorts regulatory competition, shifts the incidence of regulatory costs, and fosters a lack of transparency and accountability that undermines the rule of law.